#ifndef _LINUX_MMU_NOTIFIER_H #define _LINUX_MMU_NOTIFIER_H #include <linux/list.h> #include <linux/spinlock.h> #include <linux/mm_types.h> struct mmu_notifier; struct mmu_notifier_ops; #ifdef CONFIG_MMU_NOTIFIER /* * The mmu notifier_mm structure is allocated and installed in * mm->mmu_notifier_mm inside the mm_take_all_locks() protected * critical section and it's released only when mm_count reaches zero * in mmdrop(). */ struct mmu_notifier_mm { /* all mmu notifiers registerd in this mm are queued in this list */ struct hlist_head list; /* to serialize the list modifications and hlist_unhashed */ spinlock_t lock; }; struct mmu_notifier_ops { /* * Called either by mmu_notifier_unregister or when the mm is * being destroyed by exit_mmap, always before all pages are * freed. This can run concurrently with other mmu notifier * methods (the ones invoked outside the mm context) and it * should tear down all secondary mmu mappings and freeze the * secondary mmu. If this method isn't implemented you've to * be sure that nothing could possibly write to the pages * through the secondary mmu by the time the last thread with * tsk->mm == mm exits. * * As side note: the pages freed after ->release returns could * be immediately reallocated by the gart at an alias physical * address with a different cache model, so if ->release isn't * implemented because all _software_ driven memory accesses * through the secondary mmu are terminated by the time the * last thread of this mm quits, you've also to be sure that * speculative _hardware_ operations can't allocate dirty * cachelines in the cpu that could not be snooped and made * coherent with the other read and write operations happening * through the gart alias address, so leading to memory * corruption. */ void (*release)(struct mmu_notifier *mn, struct mm_struct *mm); /* * clear_flush_young is called after the VM is * test-and-clearing the young/accessed bitflag in the * pte. This way the VM will provide proper aging to the * accesses to the page through the secondary MMUs and not * only to the ones through the Linux pte. */ int (*clear_flush_young)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address); /* * Before this is invoked any secondary MMU is still ok to * read/write to the page previously pointed to by the Linux * pte because the page hasn't been freed yet and it won't be * freed until this returns. If required set_page_dirty has to * be called internally to this method. */ void (*invalidate_page)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long address); /* * invalidate_range_start() and invalidate_range_end() must be * paired and are called only when the mmap_sem and/or the * locks protecting the reverse maps are held. The subsystem * must guarantee that no additional references are taken to * the pages in the range established between the call to * invalidate_range_start() and the matching call to * invalidate_range_end(). * * Invalidation of multiple concurrent ranges may be * optionally permitted by the driver. Either way the * establishment of sptes is forbidden in the range passed to * invalidate_range_begin/end for the whole duration of the * invalidate_range_begin/end critical section. * * invalidate_range_start() is called when all pages in the * range are still mapped and have at least a refcount of one. * * invalidate_range_end() is called when all pages in the * range have been unmapped and the pages have been freed by * the VM. * * The VM will remove the page table entries and potentially * the page between invalidate_range_start() and * invalidate_range_end(). If the page must not be freed * because of pending I/O or other circumstances then the * invalidate_range_start() callback (or the initial mapping * by the driver) must make sure that the refcount is kept * elevated. * * If the driver increases the refcount when the pages are * initially mapped into an address space then either * invalidate_range_start() or invalidate_range_end() may * decrease the refcount. If the refcount is decreased on * invalidate_range_start() then the VM can free pages as page * table entries are removed. If the refcount is only * droppped on invalidate_range_end() then the driver itself * will drop the last refcount but it must take care to flush * any secondary tlb before doing the final free on the * page. Pages will no longer be referenced by the linux * address space but may still be referenced by sptes until * the last refcount is dropped. */ void (*invalidate_range_start)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end); void (*invalidate_range_end)(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, unsigned long end); }; /* * The notifier chains are protected by mmap_sem and/or the reverse map * semaphores. Notifier chains are only changed when all reverse maps and * the mmap_sem locks are taken. * * Therefore notifier chains can only be traversed when either * * 1. mmap_sem is held. * 2. One of the reverse map locks is held (i_mmap_lock or anon_vma->lock). * 3. No other concurrent thread can access the list (release) */ struct mmu_notifier { struct hlist_node hlist; const struct mmu_notifier_ops *ops; }; static inline int mm_has_notifiers(struct mm_struct *mm) { return unlikely(mm->mmu_notifier_mm); } extern int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm); extern int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm); extern void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm); extern void __mmu_notifier_mm_destroy(struct mm_struct *mm); extern void __mmu_notifier_release(struct mm_struct *mm); extern int __mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address); extern void __mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address); extern void __mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end); extern void __mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end); static inline void mmu_notifier_release(struct mm_struct *mm) { if (mm_has_notifiers(mm)) __mmu_notifier_release(mm); } static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address) { if (mm_has_notifiers(mm)) return __mmu_notifier_clear_flush_young(mm, address); return 0; } static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_page(mm, address); } static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_range_start(mm, start, end); } static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end) { if (mm_has_notifiers(mm)) __mmu_notifier_invalidate_range_end(mm, start, end); } static inline void mmu_notifier_mm_init(struct mm_struct *mm) { mm->mmu_notifier_mm = NULL; } static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) { if (mm_has_notifiers(mm)) __mmu_notifier_mm_destroy(mm); } /* * These two macros will sometime replace ptep_clear_flush. * ptep_clear_flush is impleemnted as macro itself, so this also is * implemented as a macro until ptep_clear_flush will converted to an * inline function, to diminish the risk of compilation failure. The * invalidate_page method over time can be moved outside the PT lock * and these two macros can be later removed. */ #define ptep_clear_flush_notify(__vma, __address, __ptep) \ ({ \ pte_t __pte; \ struct vm_area_struct *___vma = __vma; \ unsigned long ___address = __address; \ __pte = ptep_clear_flush(___vma, ___address, __ptep); \ mmu_notifier_invalidate_page(___vma->vm_mm, ___address); \ __pte; \ }) #define ptep_clear_flush_young_notify(__vma, __address, __ptep) \ ({ \ int __young; \ struct vm_area_struct *___vma = __vma; \ unsigned long ___address = __address; \ __young = ptep_clear_flush_young(___vma, ___address, __ptep); \ __young |= mmu_notifier_clear_flush_young(___vma->vm_mm, \ ___address); \ __young; \ }) #else /* CONFIG_MMU_NOTIFIER */ static inline void mmu_notifier_release(struct mm_struct *mm) { } static inline int mmu_notifier_clear_flush_young(struct mm_struct *mm, unsigned long address) { return 0; } static inline void mmu_notifier_invalidate_page(struct mm_struct *mm, unsigned long address) { } static inline void mmu_notifier_invalidate_range_start(struct mm_struct *mm, unsigned long start, unsigned long end) { } static inline void mmu_notifier_invalidate_range_end(struct mm_struct *mm, unsigned long start, unsigned long end) { } static inline void mmu_notifier_mm_init(struct mm_struct *mm) { } static inline void mmu_notifier_mm_destroy(struct mm_struct *mm) { } #define ptep_clear_flush_young_notify ptep_clear_flush_young #define ptep_clear_flush_notify ptep_clear_flush #endif /* CONFIG_MMU_NOTIFIER */ #endif /* _LINUX_MMU_NOTIFIER_H */